There is known a technique of prohibiting an automatic engine shutdown, in which, in a case where a total starter driving count T is equal to or larger than a warranty driving count of the starter, it is determined that the starter may not be normally driven (refer to JP2001-65440A). In this technique, an integral value Cm of the starter driving count in a manual start operation and an integral value Ca of the starter driving count in an automatic start operation are independently obtained, and a load ratio α:β is introduced in consideration of a load difference between the manual start operation and the automatic start operation. In addition, the total starter driving count T is computed based on the following equation.T=α×Cm+β×Ca 
In this case, a battery voltage and an engine cold state (such as engine water temperature or an outdoor air temperature) are employed as a factor that determines the load ratio α:β.